In a related dimmer, it has been known to adjust the light output of a lighting load (for example, Patent Literature 1).
A dimmer described in Patent Literature 1 includes a pair of terminals, a control circuit, a control power supply that is configured to supply the control circuit with control power, and a dimming operation device that is configured to set a dimming level of a lighting load.
The control circuit and the control power supply are connected in parallel between the pair of terminals. A series circuit of an AC power supply and the lighting load is to be connected between the pair of terminals. The lighting load includes a plurality of LED (Light Emitting Diode) devices, and a power supply circuit that is configured to light each LED device. The power supply circuit includes a smoothing circuit of a diode and an electrolytic capacitor.
The control circuit includes a switch that is configured to perform phase control of AC voltage to be supplied to the lighting load, a switch driver that is configured to drive the switch, and a controller that is configured to control the switch driver and the control power supply.
The control power supply is connected in parallel with the switch. The control power supply converts the AC voltage of the AC power supply into the control power. The control power supply includes an electrolytic capacitor that is configured to store the control power.
The controller is supplied with the control power through the electrolytic capacitor from the control power supply. The controller includes a microcomputer. The microcomputer is configured to perform reverse phase control by interrupting the supply of electric power to the lighting load at an intermediate time point in each half cycle of AC voltage.